[W4HM Spaceweather] W4HM HF Radio Wave Propagation Forecast #98
Thomas F. Giella
thomasfgiella at gmail.com
Sun Apr 23 12:07:40 EDT 2017
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#98 Issued on Sunday April 23, 2017 at 1600 UTC
Global Daily HF Radio Wave Propagation Forecast-
HAMATEUR & SW BROADCAST HF BANDS:
Global generalized HF radio wave propagation conditions are
very poor to fair on 10-80 (11-75) meters
NORTHERN HEMISPHERE RADIO WAVE PROPAGATION-
80-60 (75-60) meters- fair at night and poor at day,
40-30 (41-25) meters- fair at night and fair at day,
20-17 (22-16) meters- very poor at night and fair at day,
15 (13) meters- very poor at night and poor at day,
12-10 (11) meters- very poor at night and very poor at day.
SOUTHERN HEMISPHERE RADIO WAVE PROPAGATION-
80-60 (75-60) meters- fair at night and poor at day,
40-30 (41-25) meters- fair at night and fair at day,
20-17 (22-16) meters- very poor at night and fair at day,
15 (13) meters- very poor at night and poor at day,
12-10 (11) meters- very poor at night and very poor at day.
Received RF signal strength scale-
Very Good- +1 over S9 Or Greater
Good- S7-9
Fair- S4-6
Poor- S1-3
Very Poor- S0
Meter Band Equivalents
Ham & SWL
160-> 90
80-> 75
60-> 60
40-> 49, 41
30-> 31, 25
20-> 22, 19
17-> 16, 15
15-> 13
12,10-> 11
The SSB RF signal levels received are based on 100 watts and ½ wave dipole
up at 40 feet for hamateur radio.
The AM signal levels on the HF shortwave broadcast bands are based on
100,000 watts (100 kw) and a typical curtain array antenna.
Please keep in mind that this is a relatively simplified HF radio wave
propagation forecast, so as to keep it easily understandable and applicable
by the average radio enthusiast.
Globally HF radio wave propagation conditions are most evenly balanced
during the fall and spring equinoxes and most diametrically opposed during
the summer and winter solstices.
Conditions also change daily, weekly, monthly, yearly and by decade, as the
sun rises and sets at different times and at different angles from the
ecliptic, as well as by radio wave frequency. This is due to changes in the
maximum usable frequency (MUF), lowest usable frequency (LUF) and F layer
critical frequency (FoF2).
The D and E layers also come into play through RF radio wave signal
absorption and refraction. And then there is sporadic E (Es) radio wave
propagation that can really throw a wrench into the gears so to speak.
Things like sporadic E (Es) radio wave propagation and lightning storm
static can impact HF radio wave propagation in an unpredictable manner and
mostly bad.
Ongoing solar, space and geomagnetic weather goings on also impact HF radio
wave propagation conditions in a negative manner.
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Solar, Space & Geomagnetic Weather Conditions On
Saturday April 22, 2017-
Solar activity was low.
Earth's geomagnetic field was at significant storming levels.
The three daily solar flux index (SFI) numbers were 82.8 83.6 82.7.
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The official daily sunspot number (SSN) was 29.
In 2017 officially there were 30 days with a daily sunspot number (SSN) of
0.
Considering that solar minimum won't occur for approximately 2 more years,
+/- 1 year, observations daily SSN's of 0 occurring now is unusually early.
In 2016 officially there were 32 days with a daily sunspot number (SSN) of
0. Considering that solar minimum won't occur for approximately three more
years, seeing daily SSN's of 0 occurring now is unusually early.
As we move forward towards the next solar minimum between solar cycle #24
and #25 the number of days with a 0 daily SSN will steadily increase.
Eventually every day for many, many, many months will see a 0, the big goose
egg.
In 2008 I forecasted solar cycle 24 to be the weakest in the past 100 years
and that forecast verified. I also forecasted that solar cycle 25 would be
virtually nonexistent, similar to the Dalton type solar minimum that
occurred in the early 1800's. It will probably be very difficult to
determine when solar cycle 24 ended and solar cycle 25 began.
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Recurrent sunspot group #12651 (#12644) was located near N11E18 with a
magnetically simple beta signature.
Sunspot group #12652 was located near N14E28 with a magnetically simple
alpha magnetic signature.
Sunspot group #12653 was located near N10E61 with a magnetically simple
alpha magnetic signature.
Unofficially there was 1 earth facing but as of yet unnumbered sunspot group
located near N08W24.
No earth facing C class or larger solar flares occurred.
No earth facing coronal mass ejections (CME) occurred.
No earth directed day side radio black outs occurred.
The twenty four hour period 3 hour interval planetary K index (Kp) was at
minor (Kp-5) geomagnetic storming conditions to active (Kp-4) geomagnetic
conditions of
5 5 5 5 5 5 4 5.
But as of Sunday April 23, 2017 the planetary K index (Kp) index has been as
high as a 6 which is moderate geomagnetic storming.
The Kp geomagnetic indices are-
0-2- quiet
3- unsettled
4- active
5- minor geomagnetic storming
6- moderate
7- strong
8- severe
9- extreme
10- our atmosphere just got cooked off like on Mars and we are all dead.
The 24 hour period maximum and minimum planetary A index (Ap) ranged between
56 and 27,
which was at major geomagnetic storming conditions to active geomagnetic
conditions.
The Ap geomagnetic indices are-
0-7- quiet
8-15 unsettled
16-29- active
30-49- minor geomagnetic storm
50-99- major
100-400- severe
>401- our atmosphere just got cooked off like on Mars and we are all dead.
The daily averaged background x-ray flux was at B3.79.
The daily averaged vertical component (Bz) of earth's magnetic field was at
-4.76 nT south.
The 24 hour period maximum and minimum disturbance storm time index (Dst)
ranged between
-35 and -62 nT.
The 24 hour period maximum and minimum solar wind speed ranged between
782 and 593 km/s
and was directly connected by a high speed solar wind stream to recurrent
(CH) coronal hole #802 (#798).
But as of Sunday April 23, 2017 the solar wind speed has been as high as
795.3 km/s.
There was a recurrent southern hemisphere (geoeffective) directly earth
facing (CH) coronal hole #802 (#798). It produced moderate (Kp-6)
geomagnetic storming during its last trip across the earth facing side of
the sun and is doing the same this time around also.
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GENERAL GUIDELINES CONCERNING CORRELATION OF PROPAGATION INDICES TO ACTUAL
HF PROPAGATION CONDITIONS-
NOTE!!! The propagation indices "interpretations" are my personal
intellectual property. Therefore the radio wave propagation indices
interpretations contained herein is copyrighted © 1988-2017 by Thomas F.
Giella, W4HM, all rights reserved. Reproduction of information herein is
allowed without permission in advance as long as proper credit is given.
All 14 of the following indices have to occur as described below in order to
see the best global high frequency radio wave propagation possible,
something that happens rarely.
1.) Dropping geomagnetic field indices numbers are better, Kp of 0 best.
2.) A daily sunspot number of 150 or higher, 200 or higher best.
3.) A daily sunspot number of greater than 100 for routine stable formation
of the E Valley/F Layer ducting mechanism.
4.) Previous 24 hour Ap index under 10, fewer than 7 for several days
consecutively are best.
5.) Previous 3 hours Kp index fewer than 3 for mid latitude paths, fewer
than 2 for high latitude paths, 0 for several days consecutively is best.
6.) Energetic protons no greater than 10 MeV (10+0).
7.) Background x-ray flux levels greater than B1 for several days
consecutively, greater than C1 best.
8.) No current STRATWARM alert.
9.) Interplanetary magnetic field (IMF) Bz with a (positive number) sign,
indicates a lesser chance of high latitude path aurora
absorption/unpredictable refraction or scattering of medium frequency RF
signals, when the Kp is above 3.
10.) A -10 or better towards a positive number Dst index during the recovery
time after a geomagnetic storm, as related to the equatorial ring current. A
positive number is best.
11.) Rising positive T index number. The T Index tracks with the F2 layer
critical frequency (foF2) and sunspot number (SSN) and indicates the
capability of the F2 layer to refract RF signals.
12.) Galactic cosmic rays decrease to -3 units below zero and trending
towards zero.
13.) Energetic electron flux levels no greater than 2 MeV (2+0).
14. A solar wind speed of less than 300 km/s for several days consecutively.
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Standard Disclaimer-
Note! I use error prone RAW public domain data from the NOAA Space
Environment Center, other U.S. government entities and educational
institutions, to produce my comprehensive HF radio wave propagation
forecast. This data is gathered and made public by the U.S. Government using
taxpayer $$$ (including mine).
However the propagation forecast that I produce from the RAW public domain
data is my personal intellectual property. Therefore this radio wave
propagation forecast contained herein is copyrighted © 1988-2017 by Thomas
F. Giella, W4HM.
Feel free to redistribute this solar, space and geomagnetic weather
discussion and HF radio wave propagation forecast, as long as you
redistribute it in it's entirety and give me credit for it.
Also solar, space and geomagnetic weather forecasting is still an inexact
science. The forecasts are not official but for educational and hobby
related purposes only and are subject to human error and acts of God,
therefore no guarantee or warranty implied.
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